Furnace and loading mechanism



Feb. 26, 1963 R. E. BUCKHOLDT FURNACE AND LOADING MECHANISM Filed March 11, 1960 6 Sheets-$heet 1 9| INVENTOR. ROBERT E. BUCKHOLDT X M 3 4 MM ATTORNEY.

Feb. 26, 1963 R. E. Buc HoLb'r macs AND ppgnmc MEQHANISM 6 Sheets-Sheet 2 Filed March 11, 1960 FIG.

IN V EN TOR.

ROBERT E. BUCKHOLDT ATTORNEY.

Feb. 26, 1963 R. E. BUCKHOLDT FURNACE AND LOADING MECHANISM 6 Sheets-Sheet 3 Filed March 11, 1960 INVENTOR. ROBERT E. BUCKHOLDT as, San.

ATTORNEY.

Feb. 26, 1963 R. E. BUCKHQLDTY 3,079,135 FURNACE AND LOADING MECHANISM 6 Sheets-Sheet 4 Filed March 11, 1960 INVENTOR. ROBERT E. BUCKHOLDT Xfl- QH ATTORNEY.

R. E. BUCKHOLDT FURNACE AND LOADING MECHANISM Feb. 26, 1963 Filed. March 11. 1960 6 Sheets-Sheet 5 Sum mm INVENTOR- ROBERT E. BUCKHOLDT ATTORNEY.

Feb. 26, 1963 R. E. BUCKHOLDT 3 FURNACE AND LOADING MECHANISM Filed March 11, 1960 6 Sheets-Sheet 6 FIG. 8

INVENTOR. ROBERT E. BUCKHOLDT ATTORNEY.

United States Patent 3,079,135 FURNACE AND LQADHNG MECHANISM Robert E. Bnckholdt, Ahington, Pa, msignor to Selas (Iorporation of America, Bresher, Pa, a corporation of Pennsylvania Filed Mar. 11, 1965, Ser. No. 14,495 33 Claims. (Cl. 263-7) The present invention relates to industrial furnaces, and more particularly to the construction of a rotary hearth furnace and apparatus for placing metal objects such as billets into the furnace and removing them therefrom.

Large rotary hearth furnaces are in extensive use today for the heating of metal objects such as billets for hot Working. One difficulty with furnaces of this type is the difiiculty of reaching the hearth upon which the work rests for repair and replacement. Another difficulty is encountered in accurately placing work on and removing it from the hearth.

With the furnace of the present invention, the roof and side walls, forming one unit, are mounted in an elevated position. The rotating hearth and its driving mechanism, forming another unit, are mounted under the roof in such a fashion that they can be raised into operative position, or lowered, to give unobstructed access to the furnace interior. The loading and unloading mechanism is so arranged that billets are simultaneously inserted into and removed from the furnace at spaced points on the hearth. The billets are moved radially of the furnace, and are placed on and removed from specific locations on the hearth in a predetermined sequence.

It is an object of the invention to provide a rotary hearth furnace in which the hearth can be moved from an operative position, where it is sealed with respect to the side walls and roof, to another position in which the interior of the furnace is completely accessible for inspection and repair.

It is a further object of the invention to provide a mechanism for accurately placing work onto and removing it from the hearth of a furnace that is particularly adapted for use with a rotary hearth.

The various features of novelty which characterize my invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, however, its advantages and specific objects attained with its use, reference should be had to the accompanying drawings and descriptive matter in which I have illustrated and described a preferred embodiment of the invention.

In the drawings:

FIG. 1 is a top view of the furnace and the furnace charge and discharge mechanism,

FIG. 2 is a section through the furnace taken on line 2 2 of FIG. 1,

FIG. 3 is a side view of the charge and discharge mechanism snowing its relation to the furnace,

FIG. 4 is a top view of the charge and discharge mechanism and a portion of the furnace,

FIG. 5 is a view of the charge and discharge mechanism taken on line 5-5 of FIG. 4,

FIG. 6 is a view of the clamp actuating mechanism,

FIG. 7 is a view of the billet clamping mechanism, and

FIG. 8 is a diagrammatic view of the piping connections for the hydraulic actuating mechanism.

Referring to FIG. 1 of the drawing, there is shown a top view of a circular hearth furnace ll, which has located in front of charge and discharge openings in its outer wall a charge mechanism 2 for placing billets to be heated into the furnace and for removing hot billets therefrom. Cold billets that are to be heated are moved 2 into position on a conveyor 3, while hot billets that have been removed from the furnace are placed on a conveyor 4 to be carried to a point where forging, rolling or other hot working can be performed upon them.

The furnace includes an annular structure including a roof 5, an inner wall 6 and an outer Wall 7 that, in section, are in the form of an inverted channel. These parts are constructed in accordance with ordinary furnace practice of a refractory heat resisting and insulating material that is backed up by sheet metal. The entire struc ture is supported in an elevated position by a structural steel framework indicated at 8. The furnace is heated by burners 9, which are located at spaced points around the roof. These burners may be of any suitable type, but are preferably of the type shown in Furczyk Patent 2,855,033. The products of combustion are removed from the furnace through suitable exhaust ducts 11 that are located at spaced positions around the inner wall 6.

Cooperating with the roof and side walls to form the floor of the furnace is a rotating hearth 12-. This hearth is comprised of an annular steel framework 13 that is lined with a refractory 14. The upper surface of the hearth, which lies between side walls 6 and 7, is composed of a series of wear resisting and high temperature bricks that are placed at different levels. It will be seen that the inner level of bricks, indicated at 15, is slightly higher than the central layer 16, which in turn is higher than the outer annular layer of bricks 17. The surface of the hearth formed by the bricks l5, l5 and 17 form a pair of annular supporting surfaces upon which the billets are placed to be heated. It will be seen from FIG. 2 that an inner row of billets, indicated at A, rests partly upon bricks i5 and 15, while an outer row of billets, indicated at B, rests upon bricks 16 and 17. By placing the billets on the hearth shaped in the manner described above, the majority of the lower surface of each billet is out of contact with the hearth, so that there will be a minimum of heat transmission between the billets and the hearth, and so that products of combustion can pass between them. This arrangement also permits the billets to be inserted and removed easily from the furnace in a manner that will be described below. The space between the outer edges of the hearth and the lower edges of walls 6 and 7 are closed by suitable seals in order to prevent infiltration of air into the furnace chamber. As shown herein, the seals consist of 21 depending flange 18 attached to the outer edge of each of the annular walls, which flanges are received in troughs 19 extending around the peripheries of the structural work 13 forming hearth 12. The troughs will be filled with any suitable sealing compound or material.

The hearth 12 is supported for rotation on a plurality of rolls 21, which ride on a circular track 22. These rolls are journaled in bearings 23 that are attached to the bottom of frame 13. Track 22 rests upon a steel framework 24. The hearth is kept concentric with the track and its frame 24, as well as with the upper part of the furnace, as it is rotating by means of rollers 25 that are attached to the inner frame members or structural work 8 that supports the top of the furnace. These rollers are engaged by a circular rail 26, which extends around the inner periphery of the structural frame 13 of the hearth. The entire hearth is rotated in steps with respect to the roof and side walls by any conventional means, and at a rate depending upon the size of the bille to be eated, the temperature to which they are heated, and the speed of operation of the load and unload mechanism. The rotating means is shown diagrammatically herein as comprising a motor 3t that is mounted on one of the frames 31 to move with the hearth. This motor drives a pinion 3dA that meshes with a circular rack 13A on the outer surface of frame 13. The motor can be energized at suitable intervals by any conventional motor control.

The annular hearth and its supporting and driving mechanism may be lowered with respect to the'side Walls and roof in order that the various parts of the furnace will be accessible for inspection and repair, if such is necessary. To this end the framework is mounted upon a series of hydraulic elevators, each of which consists of a plunger or piston 27 that is received in a hydraulic :cylinder 28, which in turn may be recessed in the foundations below the furnace. The hydraulic fluid used to raise and to lower the hearth is supplied to each of the elevator mechanisms simultaneously, so that the .entire hearth will be kept level as it is raised and lowered. If desired, some mechanism, such'as is used on automobile lifting racks, can'be incorporated with the lifting mechanism in order to insure .that each of the lifting mechanisms'will be operated at the same speed. The hearth is guided as. it is being raised and lowered by means .of rollers 29 that arejournaled for rotation in supplemental frames 3i, which extend radially at spaced points around frame 24. Rollers 29 will bear against plates 32 fastened to the inside of the outer supports 8,,while the edges of frame 31 will engage suitable wear plates fastened to the sidesof the supports 8. Thus, the frame uponwhich track 22 is supported will be mounted concentric with the furnace framework as it is being raised and lowered, .andthe side members of the radially extending frame 31 cooperating with frame 8 will prevent rotation of the frame carrying the track.

The outer wall 7 of the furnace is proved with a dis charge opening 33 and charge opening 34 (FIG. 4), through which the billets to be heated are removed and inserted, respectively. Referring to FIG. 1, if the hearth is rotated in a counterclockwise direction, billets to be heated will be placed into the furnace opening 34 at the right of the'loading mechanism, whileheated billets will be removed from the furnace through the left opening '33. Suitable doors will be provided to cover these openings between loading and unloading operations.

The loading mechanism .2 is operated simultaneously to load and unload billets into the furnace while the hearth is still'between its intermittent rotative movements.

"This mechanism'includes a car 35 having rollers 36 there- The track is so located with respectto the furnace that car 35 moves radially of. the furnace on aline midway between the loading and unloading openings provided in wall 7. The car ismoved by a hydraulic system including a cylinder 35! attached to the car at its end away from the furnace by a pivotedconnection 41. Received in the cylinder is a piston (not shown) that is midway between the ends of stationary piston rod 42 fastened by bolts 43 to abutments 44 rigidly mounted on the ends of frame 38. Hydraulic fluid is introduced intotheright end of the cylinder through a flexible tube 45 and into the left end of the cylinder by a flexible tube 46. Introducing fluid through tube 45 will move the car radially toward the furnace, while introducing fluid through tube '46 willmove the car radially away from the furnace.

Billets are placed in and removed from the furnace by "a pair of similar peels shown generally at 47 and 48, re-

spectively. These peels are carried by car 35, and are so mounted thereon that they Will-be radial to the furnace charging position, each peelcan cooperate with billets on the hearth in either row A or row B.

Peel 47 includes a carriage 4& formed of a structural steel member including arms 51 and 52 extending therefrom. These arms are joined at their outer ends by a .zontal flange of rail 81.

member 53 to form a rigid frame that supports the peel for its movement relative to the car. The arms 51 and 52 are received by and move in a pair of guides 54 and 55 fixed to the top of the car. These guides are provided with vertically extending rollers 56 to guide the carriage in its movement toward and away from the car, and with horizontally extending rollers 57 to maintain the peel at a fixed vertical elevation. I

Carriage 49 has a yoke 58 on the front thereof and a yoke 59 at its rearward end, which yokes are each provided with pairs of rollers 61 to support a billet carrying assembly for movement on the carriage radially of the furnace. The billet carrying assembly consists of an ibeam '62, carried by rollers 61, to which is attached a tubular supporting member .63 that extends toward the furnace. Since the front end of the tubular member moves into and out of the furnace as billets are to be placed on the hearth, the front end is surrounded by a sleeve .64 leaving an annular space around tube as through which cooling water can be circulated.

Thej'billet carrying assembly is moved radially of the furnace on its carriage by means of a hydraulic system, which includes a cylinder 65 pivoted at 66 to yoke 59. A piston rod 67, connected to a-piston in the cylinder, is attached by a yoke 68 on its front end through a pivot 69 and an attaching member 71 to the upper flange of I-beam 62. Fluid can be supplied to the front end of cylinder 65 through a tube 72 and to the rear. end'thereof through a tube 73. Therefore, as fluid is supplied to one or the, other of the tubes, the I-beam 62 and the parts attached thereto are moved with respect to the carriage 49.

The loading peel 48 is subsantially identical topeel 47, except that itis mounted on .the opposite side of car 35. This peel is also mounted for movement on the car in such a fashion that it remains radial to the furnace opening 33 regardless of the position of the car. Since peel 48 is substantially identicalto peel 47, like parts have been designated with the same reference numeralswith an A added thereto. In this case, fluid is introduced into the front ofcylinder 65A through atube 74, and-fluid is introduced into the rear end of 65A through a tube 75.

The peels 47 and .48 are moved-perpendicularlyto the travel of the carriage35 as that carriage is moved toward and away'from the furnace by a follower that cooperates with a stationary guide rail. Referring to the-drawings, and in particular FIG. 5,.there is. shown attached to carriage 49 a downwardly extending arm 76, which has a follower 77- pivoted to its lower end by a pin 78. This follower carries a pair of rollers 79 that engage opposite sides .of .an upstanding flange on a guide rail 81. The rail ismounted on one of the members of frame 38 at such an angle to this frame that the carriages for the peels will be kept radial with the furnace as car 35 is moved. To this end the rail is mounted on a pair of supports 82 and 83 by means of bolts 84. The bolts are threaded into the supports and passed through slots 85 in the hori- The'use of these slots permits accurate adjustment of the rail, so that the carriages can be properly adjusted.

Each peel is provided on its front end with a clamp to hold a billet which is to be placed in-or removed from the furnace. As shown best in FIG. 7, the clamp includes a fixed arm'86 rigidly mounted upon the front end of tube 63, and a movable arm 87 that is attached to the front end of a shaft 88 which extends through tube 63 and is journaled therein. The shaft ,88:is rotated in order to grasp a billet between arms 86 and 87 by means of a hydraulic system including a cylinder 89 that is pivoted at 91 on supports 92, which. are rigidly attached to the rear end of beam 62 A piston is received in the cylinder 39', and has on its lower end a piston rod 93 that is pivoted to the outer end of a lever Q4 rigidly attached to the rearend of shaft 88. Therefore, as fluid is supplied to or discharged from the opposite ends of cylinder 89, arm

'87 willbe movedwith respect to arm 86 to grasp or release a billet. The rotation of shaft 88 in one direction is limited by an abutment 95 on the opposite end of arm 94, which engages a stop 96 in the form of a bolt that is threaded through a suitable member fastened to beam 62. Fluid can be admitted to and discharged from opposite ends of cylinder 89 through tubes 97 and $8, respectively.

The gripping mechanism on peels 47 and 48 is identical, and the mechanism on peel 48 is given the same reference numerals as that on peel 47 with the addition of A, with fluid being supplied to opposite ends of cylinder 89A through tubes 99 and 101.

The operation of the apparatus will be described with particular reference to H6. 8, which shows the various movable parts diagrammatically and the hydraulic connections. In describing a cycle of operations, assume that the furnace hearth has just completed a step of counterclockwise rotation to place two hot billets, one in each of the inner and outer rows on the hearth, in front of opening 33, and place an empty space on the hearth in front of opening 34. In this condition, car is retracted from the furnace, peel 47-is moved forward on its carriage so that the clamp will cooperate with the inner billet row, while peel 48 is moved back on its carriage to cooperate with the outer billet row. The clamp on peel 47 will be closed to grasp a cold billet on conveyor 3, while the clamp on peel 48 will be open.

Fluid to the various cylinders is controlled by three four-way valves 162, 103 and 104-. These valves will direct fluid, generally oil, to one end or the other of the cylinders, from a source of supply under pressure through pipe 185, and from the cylinders through pipe 106 to a suitable reservoir. With the parts in the positions described above, the valves will be in the positions shown.

Valve Elli will be rotated to connect the fluid supply with tube and the exhaust with tube 46. Fluid will then flow in the right end of cylinder 39 to move car 35 toward the furnace. As the car moves, the peels will move on the car toward each other to maintain their radial position with respect to furnace openings 33 and 34. This movement will continue until the car reaches the end of its travel, at which time the clamp of peel 47, holding a billet, will be over a position on row A, and the clamp of peel 48 will be above a position on row B of the hearth.

Valve 164 is then rotated to connect tubes 98 and it'll with the pressure supply, and tubes 97 and 99 with the exhaust. This will move arm 87 away from arm 86 to deposit a billet in row A on the hearth, and will move arm 87A toward arm 86A to grasp a billet in row B on the hearth. Valve 1G3 is then rotated back to the position of FIG. 8, so that fluid can flow into the left end of cylinder 39 to retract car 35. Valve 104 is rotated to the position shown, so the hot billet in the clamp of peel d8 is released and placed on conveyor 4- for transfer to a hot working location, and the clamp on peel 57 is closed to grasp another cold billet on conveyor 3.

At this time, valve 102 is rotated to connect the supply of fluid with tube 72 to retract peel 47 on its carriage, and with tube 75 to move peel d3 forward on its carriage. In this condition, when car 35 is moved toward the fun nace, peel 47 will be in position to place a billet on the outer row B of the hearth, while peel 48 is in position to remove a hot billet from the inner row A. Valve 103 is then rotated to supply fluid through tube 45 to move car 35 toward the furnace. The clamp on peel 47 is then opened, by rotation of valve 104, to deposit a billet in the outer row on the hearth, and to cause the clamp on peel 48 to grasp a hot billet in the inner row. Actuation of valve 1% again will cause the car to move outward, so the hot billet can be deposited on conveyor 4 and a cold one on conveyor 3 can be grasped.

At this time, the furnace hearth in front of opening 33 will be empty, and in front of opening 34 will have two billets on it. The hearth will then be rotated another 6 step, so that the loading and unloading operation can be repeated. While the hearth is rotating, valve 102 will be moved back to the position shown to shift the peels to their original position. The parts will then be in position for the cycle to be repeated.

From the above, it will be seen that by manipulating the valves, billets will be simultaneously unloaded from the outer row and loaded on the inner row of the hearth. Then billets will simultaneously be unloaded from the inner row, and loaded on the outer row of the hearth at a given circumferential location. Thereafter, the furnace hearth is rotated another step, and the loading and unloading operations repeated.

The arrangement described permi-ts billets to be placed on and removed from the hearth in a plurality of radially displaced rows. It will be obvious, however, that the peels can be so adjusted on their carriages that a single row of billets can be placed on the hearth if desired, and this row can be at any point radially of the hearth. No matter what the position of the peels and the car, the peels are always positioned so the billets are moved radially with respect to the furnace.

While in accordance with the provisions-of the statutes, I have illustrated and described the best form of embodiment of my invention now known to me, it will be apparent to those skilled in the art that changes may be made in the form of the apparatus disclosed without departing from the spirit and scope of the invention set forth in the appended claims, and that in some cases certain features of my invention may be used to advantage without a corresponding use of other features.

What is claimed is:

1. Furnace loading and unloading mechanism including a car, means to move said car in a line toward a point, an elongated peel, means to mount said peel on said car at an angle to said line with said peel directed toward said point, means to move said mounting means on said car as said car is moved thereby to keep said peel directed toward said point at all positions of said car, and clamping mechanism on said peel to clamp a work piece.

'2. The combination of claim 1 in which said peel is mounted on one side of said car, a second elongated peel, means to mount said second peel on the other side of said car at an angle thereto and directed toward said point, and means to move the mounting means of said second peel relative to said car as said car moves thereby to keep said second peel directed toward said point at all positions of said car.

3. The combination of claim 2 including means to shift both of said peels on their mounting means toward and from said point.

4. In combination, a rotary hearth furnace having a hearth with a pair of concentric work receiving surfaces, said furnace being provided with a pair of circumferentially spaced openings through which work can be placed upon and removed from said hearth, a pair of peels, means to mount one of said peels for radial movement into and out of each of said openings, means to shift said peels on their mounting means alternately in a direction radial to said furnace whereby said peels will cooperate alternately with work pieces at different radial positions on said supporting surfaces for a given position of said mounting means, means to move said mounting means to carry said peels into and out of said openings, and clamp means on said peels to carry billets.

5. In combination, a rotary hearth furnace having a hearth provided With a pair of radially displaced work receiving stations, the inner of which is at a higher elevation than the outer, and having a pair of circumferentially displaced openings through which work can be placed on and removed from said hearth, a car, means to support said car for movement radially of said furnace between said openings, a pair of peels, means to mount said peels on said car so that each peel is radial to an opening, said mounting means permit-ting movement of said peels on said car as said ear is moved radially so that said peels will remain radial to said openings regardless of the position of said-car, means to shift said peels radially of said upon which billets are'to be placed, the radially inner station'being at a higher elevation, and with a pair of circumferentially spacedopenings through which billets are inserted and removed, apair of peels, means to mount said peels for radial movement toward 'andfrom said furnace, with one peel moving radially ;ofieach opening, means simultaneously to..move'said peels toplace billets on and removethem from said hearth, and'means to shift said petals alternately 'OIlISaid. mounting; means in -a direction: radialto saidffurnacewherebywhen one peel is aboveone of said :..concentric stations the secondpeel will be above the. othertconcentric station.

7. In combination with a circular furnace havinga pair "of' openings: in theiouter periphery. thereof through which work can beimoved, 'a car,.means .tov mount saidcar for movement radially:of: saidfurnace. between said openings, means tonrovezsaid car;toward and from said furnace, .a ,peel, =meansto support said peel on .said car radially of'said furnace and aligned with-one of said openings, means to move said supporting means on; said .car as said car moves therebyito keep: said. peel; radially aligned with said opening in any'positionzofsaid car, means to move said car radially of said furnace to carrysaidzpe'el; into and outzo'fsaid opening, and clamp meansonsaidpeel to, hold apiece ,of: work to .be heated.

8. :The.cornbinationrof claim,7 .including means to. shift saidzpe'el radiallyiof saidfurnacexon saidsupporting means .tovary the position-of said peel in said furnace for a given position of said car.

:9. Apparatus :for. heating billets. comprisinga furnace having :an annular-rotary hearth shaped to'receive two .rradiallyc displaced .rows :Of .billets,,:and =acpair of spaced openings throughwhich billets can be, placed on. and, re- ;moved'fron1:the;hearth, a car, meansto mount'said car ;for-'movementradially-of said furnace at a locationbetween said openings,..a1first eeL'means to mountsaid peel on-:said car for: movementin such a manner that it rwillpremain-radialto one 76f said openings asrsaid car moves, a second peel, means tozmou'nt said second peel for movementon said carso thatrit w'illremain radial ,to the other-ofzsaid openingssas said car moves, means to move said car to carry said peels into and outiof said ropenings, means to;movegsaid mounting means on said car as said car is moving, and means on said-peels to y grip billets.

10. The combination of claim 9 including means to move said peels on their mounting means radially of said furnace a distance adapted to be substantially equal "to the radial distance between the rows of'billets on said hearth.

*ata point betweenrsaid openings, a pair of peels, means to mount each peel onsaid car radial to one of said openings, means to move said peels axially on said mounting-means a distance adapted to be equal to the radial distance betweensaid rows of work pieces, means tomove said car to movesaid peels into and out of the openings of said furnace, and meanson said peels to hold Work pieces formovement into and out of the furnace.

13. In a rotary hearth furnace,structure forming an annular roof with depending side walls, vertical structural members supporting said structure in an elevated position, an annular hearth cooperating with said side walls to form an annular furnace chamber, a frame concentric with and below said hearth, track and roller means carried by said frame andrhearth whereby said hearth can rotate on said frame and relative to said structure, cooperating means between said hearth and said structural members to maintain said hearth concentrio with said structure, radial arms extending from said frame to engage said structural members and thereby prevent rotation of said frame as said hearth rotates, means to raise and lower said frame, and cooperating means between said radial arms and structural members to guide said frame as it is being raised and lowered.

References Cited in the file of this patent UNITED STATES PATENTS 906,416 Harkins Dec. 8, 1908 1,691,367 Baker Nov. 13, 1928 2,074,662 McLay Mar. 23, 1937 2,293,549 Keener Aug. 18, 1942 2,499,926 Lloyd Mar. 7, 1950 2,980,412 Koerner Apr. 18, 1961 FOREIGN PATENTS 570,372 Great Britain July 4, 1945 869,974 Germany Mar. 9, 1953 

1. FURNACE LOADING AND UNLOADING MECHANISM INCLUDING A CAR, MEANS TO MOVE SAID CAR IN A LINE TOWARD A POINT, AN ELONGATED PEEL, MEANS TO MOUNT SAID PEEL ON SAID CAR AT AN ANGLE TO SAID LINE WITH SAID PEEL DIRECTED TOWARD SAID POINT, MEANS TO MOVE SAID MOUNTING MEANS ON SAID CAR AS SAID CAR IS MOVED THEREBY TO KEEP SAID PEEL DIRECTED TOWARD SAID POINT AT ALL POSITIONS OF SAID CAR, AND CLAMPING MECHANISM ON SAID PEEL TO CLAMP A WORK PIECE. 